Great achievement, especially considering that you only had 12 hours and were alone. The concept with the shape shifting is really cool. Although when I first read it I tought the player would actually change in physical size and shape, which might make the puzzles even more intersting. Also I don't understand why there is a cooldown on the shape shifting.
I think I got stuck a few times (mostly as a triangle shape) - might be worth investigating, depending on how busy you are after the jam :)